/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.expression.spel.ast;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;

import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Operation;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.util.Assert;
import org.springframework.util.NumberUtils;

/**
 * Implements division operator.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @author Giovanni Dall'Oglio Risso
 * @since 3.0
 */
public class OpDivide extends Operator {

    public OpDivide(int pos, SpelNodeImpl... operands) {
        super("/", pos, operands);
    }


    @Override
    public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
        Object leftOperand = getLeftOperand().getValueInternal(state).getValue();
        Object rightOperand = getRightOperand().getValueInternal(state).getValue();

        if (leftOperand instanceof Number && rightOperand instanceof Number) {
            Number leftNumber = (Number) leftOperand;
            Number rightNumber = (Number) rightOperand;

            if (leftNumber instanceof BigDecimal || rightNumber instanceof BigDecimal) {
                BigDecimal leftBigDecimal = NumberUtils.convertNumberToTargetClass(leftNumber, BigDecimal.class);
                BigDecimal rightBigDecimal = NumberUtils.convertNumberToTargetClass(rightNumber, BigDecimal.class);
                int scale = Math.max(leftBigDecimal.scale(), rightBigDecimal.scale());
                return new TypedValue(leftBigDecimal.divide(rightBigDecimal, scale, RoundingMode.HALF_EVEN));
            }
            else if (leftNumber instanceof Double || rightNumber instanceof Double) {
                this.exitTypeDescriptor = "D";
                return new TypedValue(leftNumber.doubleValue() / rightNumber.doubleValue());
            }
            else if (leftNumber instanceof Float || rightNumber instanceof Float) {
                this.exitTypeDescriptor = "F";
                return new TypedValue(leftNumber.floatValue() / rightNumber.floatValue());
            }
            else if (leftNumber instanceof BigInteger || rightNumber instanceof BigInteger) {
                BigInteger leftBigInteger = NumberUtils.convertNumberToTargetClass(leftNumber, BigInteger.class);
                BigInteger rightBigInteger = NumberUtils.convertNumberToTargetClass(rightNumber, BigInteger.class);
                return new TypedValue(leftBigInteger.divide(rightBigInteger));
            }
            else if (leftNumber instanceof Long || rightNumber instanceof Long) {
                this.exitTypeDescriptor = "J";
                return new TypedValue(leftNumber.longValue() / rightNumber.longValue());
            }
            else if (CodeFlow.isIntegerForNumericOp(leftNumber) || CodeFlow.isIntegerForNumericOp(rightNumber)) {
                this.exitTypeDescriptor = "I";
                return new TypedValue(leftNumber.intValue() / rightNumber.intValue());
            }
            else {
                // Unknown Number subtypes -> best guess is double division
                return new TypedValue(leftNumber.doubleValue() / rightNumber.doubleValue());
            }
        }

        return state.operate(Operation.DIVIDE, leftOperand, rightOperand);
    }

    @Override
    public boolean isCompilable() {
        if (!getLeftOperand().isCompilable()) {
            return false;
        }
        if (this.children.length > 1) {
            if (!getRightOperand().isCompilable()) {
                return false;
            }
        }
        return (this.exitTypeDescriptor != null);
    }

    @Override
    public void generateCode(MethodVisitor mv, CodeFlow cf) {
        getLeftOperand().generateCode(mv, cf);
        String leftDesc = getLeftOperand().exitTypeDescriptor;
        String exitDesc = this.exitTypeDescriptor;
        Assert.state(exitDesc != null, "No exit type descriptor");
        char targetDesc = exitDesc.charAt(0);
        CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, leftDesc, targetDesc);
        if (this.children.length > 1) {
            cf.enterCompilationScope();
            getRightOperand().generateCode(mv, cf);
            String rightDesc = getRightOperand().exitTypeDescriptor;
            cf.exitCompilationScope();
            CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, rightDesc, targetDesc);
            switch (targetDesc) {
                case 'I':
                    mv.visitInsn(IDIV);
                    break;
                case 'J':
                    mv.visitInsn(LDIV);
                    break;
                case 'F':
                    mv.visitInsn(FDIV);
                    break;
                case 'D':
                    mv.visitInsn(DDIV);
                    break;
                default:
                    throw new IllegalStateException(
                            "Unrecognized exit type descriptor: '" + this.exitTypeDescriptor + "'");
            }
        }
        cf.pushDescriptor(this.exitTypeDescriptor);
    }

}
